Mass storage optical disc systems, such as rewritable or recordable DVDs, have been developed and available on the market. The DVD-RAM, DVD-RW, and DVD-R are examples of the rewritable or recordable DVDs. In the optical disk system, a pulse train which varies in accordance with information to be recorded is converted into a pulse train which is smaller than a smallest unit of the information. Then, a strength of a laser beam is subjected to intensity modulation in accordance with the smaller pulse train, and the laser beam whose strength is modulated is focused onto a medium. The laser beam heats up the medium so as to cause properties of the medium to change. As a result, the information is recorded on the medium. Here, in the optical disk, recording condition setting information is recorded beforehand as standard recording conditions. This recording condition setting information is for compensating pulse width and strength of the laser beam needed for the recording.
Incidentally, with the increasing storage density of the optical disk, it becomes more necessary that the standard recording conditions be delicately set for each combination of a record-mark and a space, or for each record-mark length.
However, due to changes in environment and uneven properties of parts being used, properties of each of mass-produced optical disk recording/reproducing devices are not always the same. Similarly, properties of the respective optical disks being mass-produced may be uneven. This may cause uneven formation of the record-mark on the respective optical disks even if the record-mark is formed under uniform recording conditions. Accordingly, some combinations of the mass-produced optical disk and the mass-produced optical disk recording/reproducing device being used as they are may not carry out appropriate recording, and may result in defective quality, even in a case where properties of the optical disk are standard, and the standard recording conditions are set by using the optical disk recording/reproducing device having the standard properties.
In order to solve the foregoing problem, Japanese Unexamined Patent Application No. 200418/2000 (Tokukai 2000-200418; published on Jul. 18, 2000) discloses a method in which recording-pulse conditions are determined by modifying standard recording-pulse conditions. In the method, the standard recording-pulse conditions are corrected by causing a predetermined amount of change in (i) positional information of all of the combinations of a space length and the record-mark length, or (ii) the positional information of one of the combinations, the each piece of the positional information in the standard recording-pulse conditions being stored beforehand in the optical disk, so that values of the recording-pulse conditions causes a jitter value to not exceed a tolerance. These values obtained by correcting the standard recording-pulse conditions are set as the recording-pulse conditions.
Incidentally, in one of techniques in the foregoing optical recording condition setting method, (i) the positional information of all of the combinations of the space length and the record-mark length, or (ii) the positional information of one of the combinations is changed by the predetermined amount.
However, in a case where properties for forming the record-mark are different depending on the record-mark length, a predetermined change uniformly added may not result in appropriate formnations of the record-marks of the respective record-mark lengths.
Further, in another technique in the method disclosed in the foregoing Tokukai, the predetermined change is added to one of combinations of the space lengths and the record-mark lengths. However, only some of the record-marks having the same record-mark length are improved. This resulted in an insufficient improvement in the quality of the reproduced signals reproduced from the overall spaces and the record marks.
Further, only a parameter (recording-pulse parameter) for pulse width is optimized, and a parameter (recording-power parameter) for recording power included in the recording conditions is not optimized.